Serwis Infona wykorzystuje pliki cookies (ciasteczka). Są to wartości tekstowe, zapamiętywane przez przeglądarkę na urządzeniu użytkownika. Nasz serwis ma dostęp do tych wartości oraz wykorzystuje je do zapamiętania danych dotyczących użytkownika, takich jak np. ustawienia (typu widok ekranu, wybór języka interfejsu), zapamiętanie zalogowania. Korzystanie z serwisu Infona oznacza zgodę na zapis informacji i ich wykorzystanie dla celów korzytania z serwisu. Więcej informacji można znaleźć w Polityce prywatności oraz Regulaminie serwisu. Zamknięcie tego okienka potwierdza zapoznanie się z informacją o plikach cookies, akceptację polityki prywatności i regulaminu oraz sposobu wykorzystywania plików cookies w serwisie. Możesz zmienić ustawienia obsługi cookies w swojej przeglądarce.
In this tutorial we discuss metamaterials and metasurfaces with balanced loss and gain, yielding unusual electromagnetic responses for a variety of applications, from imaging to scattering manipulation and sensing.
The discovery of the topological phase of matter has largely influenced solid state physics, photonics and acoustics research in recent years, offering not only deep physical insights into a new generation of materials and light-matter interactions, but also new engineering tools to tailor signal transport with electrons, light and sound, providing unique features in terms of robustness to defects...
In this contribution, we explore the generation and manipulation of topological singularities of vortex fields in order to shape and rotate the radiation pattern of patch antennas. We first extend at microwaves a result already obtained at optical frequencies for which, by superimposing a constant background on a vortex field, one can modify at will the position of its phase singularity. Then, we...
Gradient metasurfaces have received significant attention in the past few years, due to their potential for advanced wave manipulation over a thin surface. Following the first, largely inefficient proposals to pattern the impinging wavefront by nanostructuring a plasmonic metasurface, to date there are several elegant approaches to design metasurfaces that can imprint a pattern of choice to the impinging...
In this contribution, we present the concept of Doppler cloak applied to narrowband antennas in order to address the issue of mismatch caused by the Doppler frequency shift. Here, we consider an antenna system composed by two antennas which are moving one with respect to the other. Our preliminary results on the observed frequency by the moving receiving antenna demonstrate that, by covering the antenna...
In this paper, we apply a reformulated version of the Surface Equivalence Principle, originally defined for radiating phenomena in terms of tangential fields, to cloaking problems in terms of admittance functions at an arbitrary boundary. In order to cloak a dielectric/metallic object, the tangential fields ratio (admittance) can be controlled at any arbitrary attached/detached surface boundary. The...
In this contribution, we investigate the effect of an infinitely-extended reactive metasurface on the complex input impedance of an electrically small dipole placed in its close proximity. We consider, as a reference scenario, the variation of the input resistance and reactance of a vertical (V-) and horizontal (H-) electric dipole placed above a perfect electric conductor for different electrical...
Electromagnetic cloaking represents one of the most fascinating possibilities enabled by metamaterials and metasurfaces. In the last years, cloaking has revealed its potentialities in many realistic applications, ranging from the design of extremely compact TLC platforms up to the compensation of the Doppler effect affecting moving objects. Here, we report some of our results about the use of electromagnetic...
In this contribution, we put forward an analytical model for the design of lossless and lossy nanoparticle-based metasurfaces working at a desired frequency in the optical spectrum. To show the versatility of our approach, we exploit it for the design of different innovative devices, such as cloaking-inspired anti-reflection coatings, circuit-analog screens and narrowband optical absorbers that are...
We study the conditions for plasmon canalization over ultrathin metasurfaces, including dispersion, polarization and energy transport phenomena. Our analysis reveals that plasmon canalization can be ideally implemented by significantly increasing either the imaginary or the real part of one diagonal component of the metasurface conductivity tensor, which enables lossy metamaterial resonances on these...
In this contribution, we report our results on the possibility of restoring the invisibility of cloaked objects in relativistic motion by using a spatio-temporal (ST-) modulated cover wrapped around or just in front of the object. It consists of an artificial dielectric whose refractive-index is modulated as a periodic function in both space and time, leading to a periodic profile of the refractive...
We investigate the use of black phosphorus thin films in infrared plasmonics and discuss spatial dispersion effects. For appropriate film thickness, black phosphorus exhibits a moderate bandgap suitable for operation in this frequency band, and the intrinsic anisotropy of its conductivity tensor provides exciting possibilities in metasurfaces/reflectarray design, such as polarization-dependent devices...
Extending the ‘flat optics’ paradigm to the nonlinear optics faces important challenges, since, for any practical situation, we are required to simultaneously achieve sub-diffraction phase control and efficient frequency conversion in metasurfaces of sub-wavelength thickness. Here, we experimentally demonstrate giant nonlinear response and continuous phase control of the giant nonlinear response in...
In this contribution, we present some important advancements in Doppler cloak technology, which is based on the frequency mixing property of linear momentum-biased metamaterial, whose artificial permittivity function is modulated in space and time. The importance of such a technology is given by the possibility to manipulate the Doppler effect and restore the invisibility of cloaked object in relativistic...
In this work the design of an ultrathin carpet cloak based on a metasurface with ring resonators is demonstrated. The scattering from a triangular bump of a Gaussian beam is suppressed by manipulating the reflection phase along the edge of the bump. This is achieved by an array of closed ring resonators with varying radii. The object to hide can be placed under the bump on a flat ground plane. The...
Non-static media have recently raised significant attention in the research community for their ability to break reciprocity without the use of magnetic fields. Different approaches to realize such media have been proposed in electromagnetics and acoustics, including mechanical motion and spatiotemporal modulation. Here, we connect these two approaches and show that they can both be derived from the...
Gradient metasurfaces have recently received significant attention for the unique opportunities they offer for advanced wave manipulation. Such metasurfaces are usually discrete implementations of surface impedance profiles, which are analytically derived to yield the desired operation. Several recent numerical and experimental studies have shown that gradient metasurfaces can work very well over...
We explore the design and realization of a topological Floquet insulator in the form of a graphene-like honeycomb network of wye resonators, in order to achieve non-reciprocal transport with zero backward reflection over a continuous frequency range. The topological insulator here consists of two domains, with different topological orders induced by a periodic spatio-temporal modulation of the resonance...
Gradient metasurfaces, or ultrathin optical components with engineered transverse impedance gradients along the surface have recently been demonstrated to provide control of the phase of scattered fields over sub-wavelength scale, enabling a broad range of linear optical components. More recently, sub-wavelength-thin nonlinear metasurfaces with tailored nonlinear responses have provided new degrees...
We propose the design of a magnet-free non-reciprocal leaky-wave antenna at terahertz (THz) frequencies based on a spatiotemporally modulated graphene monolayer. Spatiotemporal modulation is achieved through time-varying voltages applied over a set of gate electrodes beneath the graphene monolayer, providing ample freedom to impart the required effective linear momentum to the supported mode. The...
Podaj zakres dat dla filtrowania wyświetlonych wyników. Możesz podać datę początkową, końcową lub obie daty. Daty możesz wpisać ręcznie lub wybrać za pomocą kalendarza.